ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-8-6261-2008Absolute rate constant and O(<sup>3</sup>P) yield for the O(<sup>1</sup>D)+N<sub>2</sub>O reaction in the temperature range 227 K to 719 KVranckxS.1PeetersJ.1CarlS. A.11University of Leuven, Department of Chemistry, 200F Celestijnenlaan, 3001 Leuven, Belgium2810200882062616272This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/8/6261/2008/acp-8-6261-2008.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/6261/2008/acp-8-6261-2008.pdf

The absolute rate constant for the reaction that is the major source of
stratospheric NO<sub>x</sub>, O(<sup>1</sup>D)+N<sub>2</sub>O &rarr; products, has been
determined in the temperature range 227 K to 719 K, and, in the temperature
range 248 K to 600 K, the fraction of the reaction that yields O(<sup>3</sup>P).
Both the rate constants and product yields were determined using a
recently-developed chemiluminescence technique for monitoring O(<sup>1</sup>D)
that allows for higher precision determinations for both rate constants,
and, particularly, O(<sup>3</sup>P) yields, than do other methods. We found the
rate constant, <i>k</i><sub>R1</sub>, to be essentially independent of temperature between
400 K and 227 K, having a value of (1.37&plusmn;0.11)&times;10<sup>&minus;10</sup> cm<sup>3</sup> s<sup>&minus;1</sup>,
and for temperatures greater than 450 K a marked decrease in rate
constant was observed, with a rate constant of only (0.94&plusmn;0.11)&times;10<sup>&minus;10</sup> cm<sup>3</sup> s<sup>&minus;1</sup> at 719 K. The rate constants determined over the 227 K–400 K
range show very low scatter and are significantly greater, by 20%
at room temperature and 15% at 227 K, than the current recommended
values. The fraction of O(<sup>3</sup>P) produced in this reaction was determined
to be 0.002&plusmn;0.002 at 250 K rising steadily to 0.010&plusmn;0.004 at
600 K, thus the channel producing O(<sup>3</sup>P) can be entirely neglected in
atmospheric kinetic modeling calculations. A further result of this study is
an expression of the relative quantum yields as a function of temperature
for the chemiluminescence reactions (<i>k<sub>CL1</sub></i>)C<sub>2</sub>H + O(<sup>1</sup>D) &rarr; CH(A) + CO
and (<i>k<sub>CL2</sub></i>)C<sub>2</sub>H + O(<sup>3</sup>P) &rarr; CH(A) + CO,
both followed by CH(A) &rarr; CH(X) + <i>h</i>&nu;, as
<i>k<sub>CL1</sub>(T)/k<sub>CL2</sub>(T)</i>=(32.8<i>T</i>&minus;3050)/(6.29<i>T</i>+398).